As mining methods in mines, a surface mining where mining is performed from the surface of the earth and an underground mining where mining is performed from the underground are known. In recent years, the underground mining has been increasingly employed due to a decrease in a load to the environment and existence of ore in deeper places. For example, Patent Literature 1 describes a working machine, which is a vehicle that excavates ore with a bucket, enters a roadway and excavates the ore, and is then moved in the roadway in a state of holding the excavated ore in the bucket.